Question

The value of van't Hoff factor, i, for CH₃COOH solution in water will be

• A. Between 1 and 2
• B. Less than 1
• C. 2
• D. 1

Hint:

For weak electrolytes like acetic acid, the van't Hoff factor is always between 1 and 2, depending on the degree of dissociation.

Answer 1

The Correct Option is A

The given question asks about the van't Hoff factor (\(i\)) for a solution of acetic acid (CH₃COOH) in water. Let's understand the concept of the van't Hoff factor and its application to CH₃COOH:

Van't Hoff Factor Explanation:

• The van't Hoff factor, \(i\), is a measure of the extent of dissociation or association of solute particles in a solution.
• For a solute that dissociates completely into \(n\) particles, \(i = n\). For a solute that does not dissociate (or associate), \(i = 1\).
• If the solute partially dissociates, \(i\) will have a value between 1 and \(n\).

Dissociation of CH₃COOH:

• Acetic acid (CH₃COOH) is a weak acid and partially dissociates in water.
• The dissociation can be represented as: \(\text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+\).
• Assuming partial dissociation, some molecules of CH₃COOH remain undissociated, leading to a van't Hoff factor \(i\) between 1 (no dissociation) and 2 (complete dissociation).

Conclusion:

Since CH₃COOH only partially dissociates in water, the van't Hoff factor for a CH₃COOH solution in water will be between 1 and 2.

Therefore, the correct answer is: Between 1 and 2.